Principle and advantages of digital power amplifier

by:Gisen     2019-12-30

The supplier of digital power amplifier uses the already existing class D amplifier circuit, and the circuit of Class D amplifier uses FET supplier H-Bridge link. The pulse wave output by the circuit field effect is restored to obtain the original sine wave, and the supplier driving the speaker generates sound. 

Features of Digital power amplifier: digital power amplifier has the characteristics of low distortion, low noise and large dynamic range. In terms of transparency and resolution of sound quality, the tranquility of the background and the shock of low frequency are incomparable to the traditional power amplifier. 

What is the principle of Digital power amplifier: digital power amplifier processes pulse width modulation (PWM) The audio digital signal, the sound information is buried in the pulse duty cycle or pulse density. A PWM Modulation Method for audio signals is the most intuitive; Most of them use pulse density to represent the signal size. Where the pulse density is high, the voltage is high; The thin local voltage is low. The bidirectional signal can be modulated in other ways, such as duty cycle 50%, I . e. pulse width and interval width 1: 1, and the amplitude of the identification signal is zero; The duty cycle is greater than 50% and the amplitude is positive, which is the larger the value, the higher the positive amplitude; The duty cycle is less than 50%, the amplitude is negative, and the smaller the negative. Because this kind of signal does not need to be directly connected to the external device, it does not need to be completely unified in format, and each factory can be modulated according to the best scheme developed by itself. 

What is the principle of digital power amplifier? What are its advantages? The switching transistor outputs a pulse width modulation waveform. To become an audible analog audio signal, a low-pass filter with a bandwidth of 20000Hz is required, filter out the high frequency components in the pulse waveform. Generally speaking, the output voltage of power amplifier is not a problem for the withstand voltage of the selected capacitor, but the maximum allowable current of the inductor should be designed correctly. 

Advantages of Digital power amplifier: 

1.the heat dissipation structure of power amplifier can be made very small and simple, and the whole circuit can be made very small. The sound card with digital power amplifier can be directly connected to ordinary speakers on notebook computers, active speakers and audio cards, which is much more convenient to use. 

2. Digital audio signals can be amplified directly. The audio signals output on CD and DVD discs are digital, and now the player has to go through digital-to-analog transformation after decoding, and then send them out after turning them into analog audio. After using digital power amplifier, the decoded PCM digital audio signal can be directly entered into the digital signal processing circuit and processed into PWM code for amplification. The digital-analog transformation in the player and the digital-analog transformation in the digital power amplifier are omitted, which not only damages the sound quality but also reduces the cost. 

3. The volume adjustment scheme will become the dividing line of the model grade. When using the digital power amplifier technology to produce the whole machine, the simple scheme is like the traditional analog power amplifier, and the input amplitude of the analog signal is attenuated by the potentiometer, achieve volume attenuation. In this way, the quantitative bit rate of digital signals is not fully utilized, the signal-to-noise ratio decreases when the volume is low, and the dynamic range becomes smaller. And can not be used for digital audio direct input system. 

4. Digital power amplifier has a small power integrated power amplifier chip with several watts of advantages in terms of cost performance, small size and power saving. The control circuit and power switching device have been integrated and are very convenient to use. Several tens of Watts of high-power digital power amplifier chips, generally only integrated control circuit parts, high-power switching devices need to be integrated or self-configured, so that the whole machine design is flexible. In the field of h f, digital power amplifier can only be regarded as exploration, and there is still a process from commercialization. However, there is no doubt that digital power amplifier is a rising star in power amplification.

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